Java Intent Extra不等于if语句中的值

这是我在这里发布的第一个问题，所以我希望我已经彻底和清楚地解释了我所面临的问题。任何/所有的帮助都将不胜感激

以下是我正在处理的java文件：

MainActivity.java

public class MainActivity extends AppCompatActivity {

    ImageButton name1Button;
    ImageButton name2Button;
    ImageButton name3Button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); // Layout contains 3 ImageButtons "@+id/imageButton1", "@+id/imageButton2" and "@+id/imageButton3"

        name1Button = (ImageButton) findViewById(R.id.imageButton1);
        name2Button = (ImageButton) findViewById(R.id.imageButton2);
        name3Button = (ImageButton) findViewById(R.id.imageButton3);
    }

    public void onChangeScreen(View view) {
        Intent changeScreenIntent = new Intent(this, SecondActivity.class);

        if(view == name1Button) {
            changeScreenIntent.putExtra("Name", "name1");
        } else if (view == name2Button) {
            changeScreenIntent.putExtra("Name", "name2");
        } else if (view == name3Button) {
            changeScreenIntent.putExtra("Name", "name3");
        } else {
            changeScreenIntent.putExtra("Name", "Other");
            }
        startActivity(changeScreenIntent);
    }
}

public class SecondActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_layout); //Contains a TextView "@+id/textViewName"

        Intent myIntent = getIntent();
        String strName = myIntent.getExtras().getString("Name"); //Set strName to the parsed name ("name1", "name2" or "name3")
        TextView myTextView = (TextView) findViewById(R.id.textViewName);
        myTextView.setText(strName); //Sets the name parsed to a TextView //Setting the texts of the displayed TextView "@+id/textViewName" to the value of strName. This CORRECTLY shows the parsed name.

        if(strName == "name1") { // Never true, even though the value of strName is "name1"
            //Do thing if certain button clicked
            Toast.makeText(this, "You selected name1", Toast.LENGTH_SHORT).show();
        } else {
            //Do other thing if non-specified button clicked
            Toast.makeText(this, "Something went wrong", Toast.LENGTH_SHORT).show();
        }
    }
}

SecondActivity.java

public class MainActivity extends AppCompatActivity {

    ImageButton name1Button;
    ImageButton name2Button;
    ImageButton name3Button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); // Layout contains 3 ImageButtons "@+id/imageButton1", "@+id/imageButton2" and "@+id/imageButton3"

        name1Button = (ImageButton) findViewById(R.id.imageButton1);
        name2Button = (ImageButton) findViewById(R.id.imageButton2);
        name3Button = (ImageButton) findViewById(R.id.imageButton3);
    }

    public void onChangeScreen(View view) {
        Intent changeScreenIntent = new Intent(this, SecondActivity.class);

        if(view == name1Button) {
            changeScreenIntent.putExtra("Name", "name1");
        } else if (view == name2Button) {
            changeScreenIntent.putExtra("Name", "name2");
        } else if (view == name3Button) {
            changeScreenIntent.putExtra("Name", "name3");
        } else {
            changeScreenIntent.putExtra("Name", "Other");
            }
        startActivity(changeScreenIntent);
    }
}

public class SecondActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_layout); //Contains a TextView "@+id/textViewName"

        Intent myIntent = getIntent();
        String strName = myIntent.getExtras().getString("Name"); //Set strName to the parsed name ("name1", "name2" or "name3")
        TextView myTextView = (TextView) findViewById(R.id.textViewName);
        myTextView.setText(strName); //Sets the name parsed to a TextView //Setting the texts of the displayed TextView "@+id/textViewName" to the value of strName. This CORRECTLY shows the parsed name.

        if(strName == "name1") { // Never true, even though the value of strName is "name1"
            //Do thing if certain button clicked
            Toast.makeText(this, "You selected name1", Toast.LENGTH_SHORT).show();
        } else {
            //Do other thing if non-specified button clicked
            Toast.makeText(this, "Something went wrong", Toast.LENGTH_SHORT).show();
        }
    }
}

其目的如下：

• MainActivity显示3个按钮
• 用户按下3个按钮中的1个，所有按钮都会调用

  onChangeScreen

• 根据3个按钮中用于调用更改屏幕上的

  onChangeScreen

  ，会向SecondActivity传递不同的值（字符串）
• 设置要传递给SecondActivity的字符串后（使用if语句和

  changeScreenIntent.putExtra（）

  ），调用第二个Activity
• SecondActivity显示一个文本框，该文本框设置为使用

  .putExtra（）

  传递的值
• 然后使用if语句根据传递的字符串执行某些操作，该字符串基本上是基于调用SecondActivity的按钮

---

这就是问题所在。比较传递到SecondActivity的字符串的if语句“显然”不等于字符串的值（但显示的

TextView

显示了此字符串）。因此代码（替换为Toast）在if语句中从不使用。

使用

equals

而不是

=

比较字符串

使用

---

使用

等于

而不是

=

比较字符串

使用

---

始终用于比较字符串

if(strName.equals("name1"))
 Toast.makeText(this, "You selected name1", Toast.LENGTH_SHORT).show();
        } else {
            //Do other thing if non-specified button clicked
            Toast.makeText(this, "Something went wrong", Toast.LENGTH_SHORT).show();
        }

字符串的等于（）而不是==

---

喜欢编码….

始终用于比较字符串

if(strName.equals("name1"))
 Toast.makeText(this, "You selected name1", Toast.LENGTH_SHORT).show();
        } else {
            //Do other thing if non-specified button clicked
            Toast.makeText(this, "Something went wrong", Toast.LENGTH_SHORT).show();
        }

字符串的等于（）而不是==

---

享受编码的乐趣….

使用

名称1.equals（strName）

而不是

=

。如果

strName

为空，则使用

名称1.equals（strName）

而不是

=

。如果

strName

曾经是

null

您是否通过xml调用了此方法

onChangeScreen

？使用equals比较字符，使用“==”比较字符。您是否通过xml调用了此方法

onChangeScreen

？使用equals比较字符，使用“==”比较字符..我也喜欢把字符串常量放在第一位以避免空检查，即使它看起来不太好。我也喜欢把字符串常量放在第一位以避免空检查，即使它看起来不太好。